Where do you find the poke flute to wake the sleeping pokemon in Pokemon Heartgold?

Top Voted Answer

You need to get to the Radio Tower in Lavander Town. A man there will give you a radio card. Once you have it, go to the sleeping Snorlax and tune your radio to the top-most part of the screen so that you are on the Pokeflute channel. The Snorlax will wake up when you talk to it.